'EU payments should be linked to soil conservation'

Ms. Stiem-Bhatia, why are healthy soils so crucial for the climate?

They are the largest carbon sinks and important water reservoirs, even more so than forests. This is very important for climate adaptation. After all, most arable land – in Germany and worldwide – is not irrigated artificially, meaning it has to make do with natural rainfall. Healthy soil helps plants survive periods of drought, absorbs water and thus help prevent flooding.

About climate action: How much CO2 is stored in our soils?

Calculations from 2017 concluded that a total of 680 billion tons of CO2 are stored in soils and 560 billion tons in forests worldwide. Model calculations assume that soils worldwide can hold another two to five billion tons of CO2 every year. By comparison, global carbon emissions are currently around 57 billion tons.

How reliable are such figures?

Soils are a very volatile carbon sink. That much needs to be said. As soon as cultivation methods change, but also due to forest fires or droughts, the carbon can quickly escape from the soil.

And what is the situation right now? Do soils release more CO2 or store it?

There are no measurements that are accurate and comprehensive enough to provide a global overview. Whether soil releases or stores CO2 depends on many factors. Take peatlands in Germany, for example: they are largely drained and therefore release CO2. But if peatlands are rewetted, they become a CO2 sink once again.

Healthy soils help prevent flooding. Did this help during this winter's flooding disaster in Germany?

This varied greatly from region to region. In Germany, we have built on and sealed a lot of natural floodplains. Sealed soils can absorb practically no water. Despite this, 55 hectares of land continue to be converted for housing and transportation every day in Germany. We are far from the government's target of reducing this to 30 hectares by 2030 and net zero by 2050. This land policy is a problem. In addition, our intensive agriculture, which uses heavy machinery, excessive mineral fertilizers and pesticides, degrades the soil. This reduces its capacity to absorb water and hinders the important build-up of humus.

How could politics reward agriculture that preserves the humus in the soil?

EU payments under the Common Agricultural Policy (CAP) should be more closely linked to soil conservation or humus levels. In general, organic farming should receive much more financial support to make it worthwhile for farmers to make the switch and invest in soil conservation. Ultimately, they are also providing a service to society as a whole.

There are tradable carbon credits that reward the build-up of humus in the soil, similar to emissions trading. What do you think of this?

These soil carbon credits are not issued by public authorities, but by private institutions. The way they are currently designed, they are problematic for farmers, climate action, and human rights. They are often so cheap that they are not a significant income alternative for farmers and hardly an incentive for soil-conserving agriculture.

Where do you see the problems for climate action?

I see three problems: First, trading in cheap credits can easily lead to companies buying their way out of climate action. They purchase credits and mathematically offset their greenhouse gas emissions instead of actually reducing their emissions. There is also the question of how long the humus – and with it, the CO2 – remains in the soil. As soon as a farm reverts from sustainable farming to monocultures or high use of pesticides, the humus content in the soil can drop again very quickly. The CO2 stored in the soil is then released. And there is the risk of leakage: a farm cultivates a certain area sustainably and receives credits for this - but in return, it may rely even more heavily on intensive farming on the neighboring field. It would receive credits even if the overall humus level of its soil remained the same.

And what human rights problems do you see?

There have been cases in the Global South where people have been evicted from their land, which they have farmed for generations, to enable credit trading. Such credits can also reinforce gender inequalities. In many countries, landowners are primarily men, meaning women rarely benefit from compensation payments. It is important that carbon trading takes a human rights-based approach.

Land is scarce, and vast areas will be needed as sinks for the climate. How large are these areas?

Almost all national climate action commitments within the UNFCCC include measures for nature-based climate action, that is, for storing CO2 in soils and forests. If you combine them all, you get an area requirement of 1.2 billion hectares. That is about three times the size of the EU. To get closer to the net-zero target, we would have to change the type of land use on around 630 million hectares, for example, by reforesting arable land. But this is not empty land. People live there and the fields are their livelihood.

Is there even enough land to meet climate adaptation requirements, nature conservation and food security?

The various requirements are not necessarily mutually exclusive. Conservation agriculture, for example, stores more CO2 in the soil, strengthens resilience to climate change, benefits nature conservation and can increase income through crop diversification. Biodiversity, climate action and food security go hand in hand. Whether they are compatible ultimately depends very much on the type of agriculture practiced.

How realistic is it then to include soils to such an extent as a CO2 sink in national climate action targets?

Land may be scarce. But we need it for the climate. Even if we manage to phase out fossil fuels as quickly as possible, we still need nature to store CO2 in order to meet our climate targets. Healthier soils secure agricultural yields in the long term and also enable better climate change adaptation. So there is every reason to protect them better.

Larissa Stiem-Bhatia heads the program for nature-based solutions at the TMG Think Tank for Sustainability. She is the author of the recently published Soil Atlas 2024 by BUND, the Heinrich Böll Foundation and TMG.